As a result of many different physiological conditions, it is often necessary to replace joints in various parts of the body with prosthetic components. Surgical procedures for preparing bones to receive such components typically require precise shaping of portions of the bones. For example, during knee joint replacement surgery, precise resection of the ends of the femur and tibia is necessary to achieve a very close match between the surfaces remaining after removal of portions of the bones, and the mating surfaces of the prostheses. Without such precision mating, the reconstructed knee may result in misalignment (alignment that differs from optimal alignment corresponding to the patient's physical characteristics) of the femur and the tibia. Such misalignment may have a variety of undesirable consequences including discomfort to the patient, reduced mobility, and excessive wear on surfaces of the prostheses.
Cutting guides are commonly used to aid the surgeon by providing a surface across which a cutting instrument is moved to create a planar cut through a bone. Such guides permit the surgeon to achieve increased accuracy as compared to free hand bone shaping. The accuracy of the planar cut, however, is dependent upon accurate placement of the cutting guide. Therefore, it is desirable to provide a system for achieving highly accurate placement of a cutting guide to ensure precision mating between the planar cuts made through a bone and the corresponding surfaces of the prosthetic component.
The present method, apparatus, and system (hereinafter collectively referred to as “the present system”) provides, in one embodiment, a drill cylinder having a body that defines a central bore, and an element configured to be detected by an image guidance system to permit image guidance of the drill cylinder to predetermined, target locations on the bone. Using the image guided drill cylinder, the surgeon may monitor on a display the current position and alignment of the drill cylinder body as compared to the target locations, and create bores into the bone at the target locations by inserting a drill bit through the central bore of the body. Alternatively, the surgeon may insert pins through the central bore into the bone at the target locations.
The present system further provides a cutting block having a frame, a guide adjustably connected to the frame, an adjustor connected to the frame, and mounting locations defined by the frame and configured to attach to the bone at the target locations. The mounting locations include either bores for receiving the pins that were inserted into the target locations, or pins for insertion into the bores that were created using the image guided drill cylinder. Accordingly, the cutting block can be accurately placed on the bone at the target locations, which in turn accurately places the guide.
The guide defines a cutting path through which a cutting instrument is passed to create a planar cut in the bone. The position of the guide (and the cutting path) relative to the mounting locations is adjustable using the adjustor. Depending upon the embodiment, actuation of the adjuster causes linear or angular adjustment of the position and/or orientation of the cutting path relative to the mounting locations.
Additionally, the present system may include a tracking instrument having an element configured to be detected by the image guidance system and an engagement portion configured to engage the cutting path to permit image guided adjustment of the cutting path. Thus, in addition to providing accurate placement of the cutting path using the image guide drill cylinder to locate the mounting locations of the cutting block, the present system enables the surgeon to achieve even greater accuracy by providing image guided adjustment of the cutting path when the cutting block is mounted to the bone.
Additional features of the present system will become apparent and be further understood upon reading the detailed description provided below with reference to the following drawings.